Having seen the amazing BT-7 with the floating pontoons, I came up with a crazy idea.

Probably a stupid question, but what would happen if those floating pontoons on the BT had been filled with helium or hydrogen? Probably nothing on the ground, but what would have happened if a BT with helium/ hydrogen filled tanks was dropped from a slightly modified TB-3 aircraft? I know that gliding tanks were experimented with, but would this crazy idea allow a BT to float to the ground?

The rig would be the size of a Zepplin,
& given that at the time only the USA had the capability to produce commercial quantities of Helium, they would have to use Hydrogen, (only 8% more lift efficient than Helium).
That would = Large Slow Target!

They did experiment with bolting double-decker wings on to small light tanks, but I believe this was extremely dangerous to the hapless Pilot/Driver? & would rip tracks of the tank on landing.

neat idea though, steam-punk tank dirigibles!

I think you'd find that the BT-7 would plummet to the ground like a 14 tonne brick and scattered itself in tiny pieces over a wide area.

Air is 1.25 kg per Cubic metre, Water is 1000kg per Cubic Meter so your "floats" need to be 1000times more buoyant in air than in water.

ROUGHLY 1 litre of Helium will lift 1.25g at sea level, the amount it can lift will decrease with altitude as the atmosphere is thinner and ergo less buoyant.

Sooooooo to get the 14 tonne BT-7 neutrally buoyant you'd need 11,200,000 litres which is 11200 cubic meters.

A cylindrical balloon 10 meters across would need to be 142 metres long to contain enough helium, to, at sea level, make it so the tank would not rise but wouldn't sink if you pushed it off a cliff.

I guess if you could tow it to altitude and it would fall faster initially but as it got into denser air it would slow down and come to ground, or blow away.

I can imagine now the AA gunners salivating at the sight of a battalion of 142 x 10m balloons bobbing majestically towards the "drop zone" , or away from it if the winds change.

PLUS, that gas was not always readily available and very expensive to manufacturer.


~ Jeff

Hydrogen wouldn't be exactly the best gas to use on a fighting vehicle....